Sealing array

ABSTRACT

A sealing arrangement ( 14 ) has a housing gap, to be sealed, between two components ( 15, 16 ) and a seal ( 1 ) which consists of two interconnected sealing components ( 2, 3 ), a first extrusion-resistant, deformable sealing component ( 2 ) and a second more deformable sealing component ( 3 ). The first sealing component ( 2 ) has an abutment surface ( 6 ) facing the sealing surface ( 17 ) of the component ( 15 ), and a contact surface ( 9 ) for abutment on the other component ( 16 ). The second sealing component ( 3 ) abuts the first sealing component ( 2 ) and has an edge ( 4 ) projecting past the abutment surface ( 6 ). The first sealing component ( 2 ) can be pressed onto the sealing surfaces ( 17; 18 ) of the components ( 15, 16; 30, 31 ) to close the housing gap in response to system pressure. The second sealing component ( 3 ) can be sealingly pressed onto the sealing surfaces ( 17, 18 ). The sealing arrangement ( 14 ) is of simple construction and can produce an effective high pressure seal in Common Rail injectors or similar systems.

BACKGROUND OF THE INVENTION

The invention concerns a sealing arrangement for statically sealing ahousing gap between two components, in particular, in response topulsating high pressure of more than 1000 bars. This seal is suitablefor applications where it is pressure-loaded by fluid system pressuresuch as in high pressure cleaners, injection systems, Common Railinjectors, and water jet cutters.

High-pressure diesel injection systems (Common Rail injectors) requirestatic seals at different sealing points which must withstand high fuelsystem pressures (currently 1300 to 1600 bars with a tendency towards2000 bars).

The seals of highly-filled PTFE, which have been used up to now, reachtheir limits at approximately 1600 bars, since extrusion occurs athigher pressures. Sealing rings of plastic materials with higherextrusion resistance than filled PTFE require high production accuracyfor the sealing rings and/or the surrounding components and/or highsurface quality all of which are disadvantageous with respect to costsand processing safety.

It is the object of the invention to produce a more effectivehigh-pressure seal of simple construction for Common Rail injectors orsimilar systems.

SUMMARY OF THE INVENTION

This object is achieved in accordance with the invention through asealing arrangement in accordance with the independent claim. The hardcomponent is supported on the housing gap, closes it and preventsextrusion of a sealing component into that housing gap. The softercomponent is strongly deformed under existing system pressure and sealsthe housing gap. The cooperation between these two components produceshigh processing safety.

In one embodiment, the first sealing component is tensioned between anedge and a projecting step of the softer component. The hard sealingcomponent is thereby held on the second sealing component andinstallation and assembly are facilitated. As an alternative to thissnap connection, the components can be chemically bonded e.g. glued.

In another embodiment, the edge is curved. The curved edge can bepressed with increased force on the surface of the component to besealed and deformed to thereby produce secure sealing.

The first (hard) sealing component is preferably L-shaped or formed fromtwo legs subtending an angle to produce an effective support ring ofsimple construction. To facilitate assembly and increase the processingsafety, it is appropriate to securely connect the two sealingcomponents.

The first sealing component can be produced from plastic material ormetal and the second sealing component can be produced from anelastomeric material.

BRIEF DESCRIPTION OF THE DRAWING

The schematic drawing shows two embodiments of the inventive sealingarrangement which are explained in the following description.

FIG. 1a shows a cross-section of the seal, which consists of two sealingcomponents, before assembly;

FIG. 1b shows a cross-section of a sealing arrangement with installedseal according to FIG. 1a;

FIG. 1c shows the sealing arrangement according to FIG. 1b with appliedsystem pressure;

FIG. 2a shows a cross-section of another seal, which consists of twosealing components, before assembly;

FIG. 2c shows a cross-section of a sealing arrangement with installedseal according to FIG. 2a with applied system pressure.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1a (production state) shows a seal 1 assembled from twointerconnected annular sealing components 2 and 3. The first sealingcomponent 2 is produced from a hard, extrusion-resistant material, e.g.from a bendable metal or sheet metal, while the second sealing component3 consists of a soft, extrudable or even softer material. FIG. 1a showsthe unloaded state before mounting of the seal 1, whereby the sealingcomponents 2 and 3 are shown in the manufacturing state. The firstsealing component 2 is L-shaped, having two legs 4 and 5 which form anabutment surface 6 facing the sealing surface of a component (see FIG.1b) and a contact surface 7. One side of this L-shape is positivelyconnected to a portion of the second sealing component 3. A curved edge8 of the second sealing component 3 projects past a leg end 9 and thecontact surface 7. Another curved edge 10 also projects past another legend 11, with the second sealing component 3 having a greaterlongitudinal extension than the first sealing component 2. This firstsealing component 2 abuts a step 12 of the second sealing component 3via the leg end 11, and the leg 4 abuts on a shoulder 13 of the secondsealing component 3.

FIG. 1b shows the assembled state of the slightly oversized seal withoutpressure load in a sealing arrangement 14. While the sealing component 2changes only slightly, the sealing component 3 deforms considerably moresuch that the seal is fixed in the cavity. The seal 1 is pressed intothe cavity and abuts the side walls 17, 18 of the cavity which is formedby the components 15 and 16. Fixation can be effected through slightpre-pressure or by using an assembling pressure which is less than thefluid system pressure. A mechanical pre-pressure, exerted e.g. by astamp, is also feasible instead of a hydraulic assembly pressure.

After installation and under pressure load (operating state) the sealingcomponents 2 and 3 assume the shape of FIG. 1c. A sealing arrangement 14has a profiled component 15 and component 16 such that a housing gap isproduced between the component 15 and the component 16 which must besealed. Although the first sealing component 2 deforms, extrusion intothe housing gap does not occur. The sealing component 2 closes thehousing gap and abuts the softer second sealing component 3 whichassumes the actual sealing function. The angle between the legs canchange with the system pressure. The first sealing component 2 preventsextrusion into the housing gap. The seal 1 is formed such that theharder sealing component 2 closes the housing gap in response to systempressure of a fluid (e.g. fuel of an injector or hydraulic oil) andprevents extrusion of the soft sealing component 3 even for adynamically changing housing gap width (“breathing gap”). The leg 5 ofthe first sealing component 2 thereby abuts on the component 15 and theleg 4 on the component 16. Abutment via the abutment surface 6 iseffected in response to pressures exerted on the component 3 duringassembly and is increased by the existing system pressure. The gapbetween the sealing component 2 and the component 15, which may betolerance-related, is closed with the first pressure load exercised byhigh pressure P. The second sealing component 3 transfers the systempressure to the first sealing component 2 and deforms such that theoriginal gaps remain closed to always ensure abutment of the secondsealing component 2, via the abutment surface 6, on the component 16.The sealing element 3 is deformed, compressed and pressed into the freespace between the sealing surface 17 and the component surface 18. Theseal is fixed during operation e.g. in response to pulsating systempressure P. The fluid produces hydraulic sizing and shaping(hydroforming) of the seal, and mainly of the elastic sealing component3.

An unloaded seal 21 of FIG. 2a is formed from the first annular sealingcomponent 22 and the second annular sealing component 23. The secondsealing component 23 is substantially rectangular with a curved edge orprojection 24 and a step 25 such that the first L-shaped sealingcomponent 22 is partially enclosed and bordered. The edge 24 projectsbeyond an abutment surface 26. Leg ends 27 and 28 join the step 25 andthe edge 24 to provide flat abutment or flat contact between the twosealing components 22 and 23. A contact surface 29 of the first sealingcomponent 22 is provided for abutment on a profiled component.

FIG. 2c again shows deformation of the first sealing component and thematerial flux of the second sealing component 23 when the static seal 21is inserted between two components 30 and 31 for sealing a housing gapand exposed to a high pressure P acting in the axial direction. Thissealing arrangement 32 can be used e.g. in Common Rail injectors. Inparticular, the edge 24 is deformed such that a varying housing gapwidth between the components 30 and 31 is compensated for and alwayssealed. The second soft sealing component 23 assumes the actual sealingfunction while the hard sealing component 22 prevents extrusion at thehousing gap.

List of Reference Numerals

1. seal

2 first sealing component

3 second sealing component

4 leg

5 leg

6 abutment surface

7 contact surface

8 curved edge

9 leg end

10 curved edge

11 leg end

12 step

13 shoulder

14 sealing arrangement

15 component

16 component

17 sealing surface

18 component surface

21 seal

22 first sealing component

23 second sealing component

24 curved edge

25 step

26 abutment surface

27 leg end

28 leg end

29 contact surface

30 component

31 component

32 sealing arrangement

P high pressure

I claim:
 1. A seal for sealing system pressure from a housing gapbetween a first and a second housing member, the first member having afirst sealing surface at a first member side of the gap and the secondmember having a second sealing surface at a second member side of thegap, the seal comprising: a first extrusion-resistant, flexible sealingcomponent having a vault-shaped cross section, said first componenthaving a first leg which can cooperate with the first sealing surfaceand a second leg which can cooperate with the second sealing surface;and a second, deformable sealing component disposed on said firstsealing component, said second sealing component being structured anddimensioned to press against the first and the second sealing surfacesin response to the system pressure to seal the gap, wherein said firstleg and said second leg subtend an angle at a side of said first sealingcomponent facing said second sealing component, said angle decreasing inresponse to system pressure until said first leg seats flatly againstsaid first sealing surface and said second leg seats flatly against saidsecond sealing surface.
 2. The seal of claim 1, wherein said secondsealing component further comprises a step disposed proximate saidcontact surface of said first sealing component to capture said firstsealing component between said step and said edge of said second sealingcomponent.
 3. The seal of claim 1, wherein said edge is curved.
 4. Theseal of claim 1, wherein said first sealing component has an L-shapedcross-section.
 5. The seal of claim 1, wherein said first sealingcomponent is made from plastic.
 6. The seal of claim 1, wherein saidfirst sealing component is made from metal.
 7. The seal of claim 1,wherein said second sealing component is made from an elastomericmaterial.
 8. The seal of claim 1, wherein said angle is an obtuse angleprior to application of system pressure.
 9. The seal of claim 8, whereinsaid angle is substantially equal to 90 degrees after application ofsystem pressure.